One of the activities associated with the completion of an oil or gas well is the perforation of a well casing. During this procedure, perforations, such as passages or holes, are formed in the casing of the well to enable fluid communication between the wellbore and the hydrocarbon producing formation that is intersected by the well. These perforations are usually made with a perforating gun loaded with shaped charges. The gun is lowered into the wellbore on electric wireline, slickline, tubing or coiled tubing, or other means until it is at a desired target depth; e.g., adjacent to a hydrocarbon producing formation. Thereafter, a surface signal actuates a firing head associated with the perforating gun, which then detonates the shaped charges. Projectiles or jets formed by the explosion of the shaped charges penetrate the casing to thereby allow formation fluids to flow from the formation through the perforations and into the production string for flowing to the surface.
Many oil well tools deployed on tubing or coiled tubing use pressure-activated firing heads to initiate a detonation train during a desired well operation. In certain aspects, the present disclosure provides pressure-activated firing heads for situations where a differential pressure and a flow source is used to activate a well tool.